Zeke
I (MIFLAW) seem to have misrepresented myself here.
I went to a state selective school in Kent. Every year, our school - recognised as taking the intellectual "cream" locally (including a lot of the children of academics) - would get, say, 7 people into Oxbridge.
Just down the road was a cathedral-based private school which shall remain nameless but which I had seen described in an article aimed at parents looking to send their children to private school as basically being the ideal choice for kids who were nice but dim.
That school regularly got 20 or 30 people into Oxbridge.
How is that feasible? Well, one explanation is that a lot of the masters were ex-Oxbridge and so coached from a position of experience. Class sizes were also much smaller than in my state school (selective, yes, but that still means 30+ bright kids in a room instead of 30+ mixed-ability kids). My school coached me too - two of my three coaches had applied to Oxford and been rejected, the other had got a third and had nearly been drummed out for laziness after his first year.
I ended up going to Oxford myself. There were lots of students from private school there who, I could see, were no brighter or more original of thought than friends of mine who had not made the cut.
If a bright student does not want to go to Oxbridge, that's fine. But if they do want to go and lose their place to a candidate who is no stronger but whose school is better connected and more geared up to getting them a place, that's not fine.